摘要
超高温变质作用对认识大地构造-热演化以及地壳成分分异等具有重要意义。南极大陆发育典型的超高温变质作用,分布于不同的构造域。主要的超高温地质单元包括内皮尔杂岩、茹尔(赖于尔)群岛、拉斯曼丘陵、吕措-霍尔姆杂岩以及席尔马赫丘陵等。不同地质单元的超高温变质作用分布规模不同,恩德比地内皮尔杂岩的超高温变质作用分布广泛(~15000 km^(2)),而席尔马赫丘陵等地的超高温变质作用分布有限,超高温变质作用规模与出露特征的不同可能暗示了不同的成因机制与热源。各超高温地质单元中发育丰富多样的超高温矿物组合,如假蓝宝石+石英组合、斜方辉石+矽线石组合、尖晶石+石英组合以及含大隅石、刚玉、三元长石或富Al斜方辉石的矿物组合,在变质基性岩中还发育石榴子石+单斜辉石+斜长石±高钛角闪石等矿物组合。丰富多样的矿物组合为研究超高温变质作用矿物反应机制提供了重要基础。不同超高温地质单元,乃至同一超高温地质单元内不同区域的P-T-t轨迹类型不同,如有些超高温变质作用具有显著的近等温减压轨迹,而有些超高温变质作用主要记录近等压降温轨迹,反映了不同的演化历史或构造背景。南极大陆超高温变质作用可分5个期次,包括中太古代晚期(2850 Ma),新太古代末期—古元古代早期(2585~2450 Ma),新元古代早期(格林维尔期,约1000~900 Ma),新元古代晚期(泛非期早期,650~605 Ma)和新元古代末期—早古生代(泛非期晚期,570~500 Ma),与超大陆(或超级克拉通)演化存在密切联系。不同的超高温变质作用可能与板块构造演化的不同阶段有关,如弧后盆地或造山带垮塌阶段等;但超高温变质作用并不局限于现今板块构造体制。南极大陆多数超高温地质单元的研究程度还相对较低,对其矿物反应机制、变质演化轨迹、形成时代及持续时间、熔融�
Ultrahigh temperature(UHT)metamorphism is of great significance for understanding the tectono-thermal evolution and crustal composition differentiation. Typical UHT metamorphism occurred in different tectonic domains of the Antarctic continent. Major geological units that have undergone UHT metamorphism include the Napier complex, the Rauer Islands, the Larsemann Hills, the Lützow-Holm complex, the Schirmacher Hills, etc. The distribution area of UHT metamorphism varies in different geological units. The UHT metamorphism of the Napier complex in Enderby Land is widely distributed(~15000 km^(2)), while the UHT metamorphism in the Schirmacher Hills is relatively limited. The differences in area and exposure characteristics of the UHT metamorphism may suggest different formation mechanisms and heat sources. In the UHT geological units, there are diverse UHT mineral assemblages, such as sapphirine-quartz, orthopyroxene-sillimanite, spinel-quartz and osumilite, corundum, ternary feldspar or Al-rich orthopyroxene-bearing assemblages. In metabasic rocks, assemblages involving garnet-clinopyroxene-plagioclase and/or high-Ti amphibole occur at UHT conditions. The diverse mineral assemblages provide an important basis for investigating the mineral reaction mechanism of UHT metamorphism. Different UHT geological units and even different regions within the same UHT geological unit have different types of P-T-t trajectories, which may reflect different evolution histories or tectonic settings. The UHT metamorphic events in Antarctica occurred intermittently, basically in five periods: the late Mesoarchean(2850 Ma), the late Neoarchean-early Paleoproterozoic(2585~2450 Ma), the early Neoproterozoic(Grenvillian)(ca. 1000~900 Ma?), the late Neoproterozoic(early Pan-African, 650~605 Ma), the late Neoproterozoic-early Paleozoic(late Pan-African, 570~500 Ma), and were closely related to the evolution of supercontinents(supercratons). Different UHT metamorphic events may have formed at different stages of the plate tectonic evolutio
作者
王伟
赵越
魏春景
刘晓春
陈龙耀
保红
刘昕淑
曹译文
WANG Wei;ZHAO Yue;WEI Chunjing;LIU Xiaochun;CHEN Longyao;BAO Hong;LIU Xinshu;CAO Yiwen(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;Key Laboratory of Paleomagnetism and Tectonic Reconstruction,Ministry of Natural Resources,Beijing 100081,China;MOE Key Laboratory of Orogenic Belts and Crustal Evolution,School of Earth and Space Sciences,Peking University,Beijing 10087l,China)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2022年第9期3102-3119,共18页
Acta Geologica Sinica
基金
国家自然科学基金项目(编号41941004,42172068)
中国地质调查项目(编号DD20221810)联合资助的成果。
关键词
南极
超高温变质作用
矿物组合
P-T-T轨迹
构造背景
超大陆
Antarctica
ultrahigh temperature metamorphism
mineral assemblage
P-T-t trajectory
tectonic setting
supercontinent
